Only the world is being rendered
First of all, Cube and Cube.001 are hidden during rendering.
Second, the material of both Cube and Cube.001 is undefined which leads to black during rendering. Delete the Material and assign a new one, for example a diffuse shader for testing.



Changing the settings like described, I get the following result:



(OK, I also changed the position of the lamp a little bit, but nothing else)

If you want to see a "real" preview you have to activate this button: